Vacuum packaging machine

ABSTRACT

A vacuum packaging machine for performing a vacuum sealing operation on product packages, comprises a vertical stack of vacuum chambers  4  which each manage to receive at least one unsealed product package  2  and are operable to perform an independent vacuum sealing operation on the least one product package  2 . A conveyor arrangement  8, 9  is operable to load and unload a selected vacuum chamber  4  with the at least one product package, and the machine is arranged to operate the respective vacuum chambers  4  to perform the vacuum sealing operation while the conveyor arrangement is operated to load and unload another vacuum chamber  4 . The conveyor arrangement loads and unloads the vacuum chambers in sequence, and the vacuum chambers are synchronously operated to perform the vacuum sealing operation to allow the conveyor arrangement to operate continuously. The conveyor arrangement comprises at least one in-feed conveyor  8  and at least one out-feed conveyor  9  which are independently movable to select the vacuum chamber to be loaded and unloaded. There may be a plurality of in-feed conveyors  8  and a plurality of out-feed conveyors  9 . The vacuum chambers each have a sealing bar arranged along one side for sealing the product packages  2.

The present application is a 35 USC §371 application of PCT/EP99/08131filed Oct. 27, 1999, which claims the benefit of priority EuropeanPatent Application Serial No. 93308823.8 filed Oct. 28, 1998.

The present invention relates to a vacuum packaging machine forperforming a vacuum sealing operation on product packages.

Vacuum packaging machines of a known type comprise a vacuum chamberarranged to receive at least one unsealed product package and operableto perform a vacuum sealing operation on the at least one productpackage. Typically the product packages are products such as food stuffarranged in a bag formed by a heat-shrinkable film. After loading andclosing the vacuum chamber, the vacuum sealing operation normallycomprises vacuumisation, sealing the mouth of the vacuumised bags, andreintroducing air into the chamber. Then the chamber is opened and thevacuum chamber is unloaded. The product packages may then be conveyed toa heat-shrinking unit, typically a hot water tunnel or a dip tank.

The vacuumisation step typically takes at least 20–30 seconds which ismostly wasted time in the overall packaging process. During this time,the only step which can be taken is to prepare the next product packagesfor loading into the vacuum chamber, for example by conveying them ontoan in-feed conveyor. Accordingly, the vacuum packing machine causes abottle-neck in the overall packaging process.

According to the present invention, there is provided a vacuum packagingmachine for performing a vacuum sealing operation on product packages,comprising a vertical stack of vacuum chambers each arranged to receiveat least one unsealed product package and operable to perform anindependent vacuum sealing operation on the at least one productpackage.

The provision of more than one vacuum chamber in the vacuum packagingmachine allows respective vacuum chambers to perform a vacuum sealingoperation while another vacuum chamber is being loaded and/or unloaded.Therefore, the machine may minimise the wasted time in the vacuumpackaging process. Consequently, the present invention can increasethrough-put and increase productivity of a packaging line including themachine. Furthermore, by arranging the vacuum chambers in a verticalstack, this increase in productivity may be achieved withoutsignificantly increasing the floor area of the vacuum packaging machine.The extra vacuum chambers only increase the height of the machine. Thisis a significant advantage in manufacturing plants where increasing thefootprint of the vacuum packaging machine would create real problems butwhere there is normally space to increase the height of the machine.

Preferably, the vacuum packaging machine further comprises a conveyorarrangement operable to load and unload a selective vacuum chamber withthe at least one product package, the machine being operable to operatethe respective vacuum chambers to perform the vacuum sealing operationwhile the conveyor arrangement is operated to load and unload anothervacuum chamber.

The conveyor arrangement can automatically load and unload selectedvacuum chambers. Operation of one or more of the vacuum chambers whilethe conveyor arrangement is loading and unloading another vacuum chamberreduces the amount of time wasted, thereby increasing through-put andincreasing productivity of a packaging line including the machine.

Preferably, the machine is operable to operate the conveyor arrangementto load and unload the vacuum chambers in a cyclical sequence andsynchronously to operate the respective vacuum chambers to perform thevacuum sealing operation on the at least one product packages afterloading.

Such a cyclical operation allows the machine to be utilised in anautomatic continuous packaging line. It is desirable that the number ofvacuum chambers is sufficient relative to the duration of the vacuumsealing operation to allow the conveyor arrangement to operatecontinuously because this minimises the amount of wasted time. Timewastage can be reduced further by designing the conveyor arrangement toload and unload the vacuum chambers more rapidly. The describedembodiments include particularly suitable conveyor arrangements asfollows.

Preferably, the conveyor arrangement includes at least one in-feedconveyor operable to load a selected vacuum chamber with the at leastone product package.

Preferably, the conveyor arrangement includes at least one out-feedconveyor operable to unload a selected vacuum chamber with the at leastone product package, although as an alternative the in-feed conveyor maybe operable in reverse to unload a selected vacuum chamber.

Provision of separate in-feed and out-feed conveyors allows the loadingand unloading to occur simultaneously, preferably with the in-feed andout-feed conveyors being linked by an internal conveyor in each vacuumchamber.

Preferably, the at least one in-feed conveyor and/or the at least oneout-feed conveyor are vertically movable to select the vacuum chamber tobe loaded. Additionally or alternatively, the plurality of vacuumchambers are movable together relative to the conveyor arrangement toselect the vacuum chamber to be loaded and unloaded.

The conveyor arrangement may include a plurality of in-feed conveyorsand/or out-feed conveyors which are movable together. In this case, thevacuum chambers are preferably have a regular spacing and the in-feedconveyors and/or out-feed conveyors have a relative spacing equal to thespacing between the vacuum chambers. This allows more than one vacuumchamber to be loaded and/or unloaded simultaneously.

Desirably, the vacuum chambers each have a sealing bar arranged along aside of the respective vacuum chamber for sealing the at least oneproduct packages, preferably extending along the internal conveyor. Thisprevents the sealing bar from hindering loading and unloading improvesthe automatic operation of the machine because the product packagesalways have the same orientation.

Advantageously, the vacuum chambers and/or the in-feed conveyors and/orthe out-feed conveyors have a modular construction. This allows themodular parts to be added and removed in order to assemble the machinewith a variable number of the parts in order to provide a productivityand cost appropriate to the particular packaging line in which themachine is used. Thus, this modular construction increases theflexibility of the machine and allows it to be used in differentpackaging lines. This flexibility is particularly advantageous with thevacuum chambers being arranged in a vertical stack because theproductivity of the machine may be altered whilst covering the samefloor space within the manufacturing plant because only the height ofthe machine is altered.

Advantageously, each vacuum chamber comprises at least two parts whichare relatively vertically movable to open and close the vacuum chamber.This construction for the vacuum chambers is advantageous because itallows for a simple machine design, lower manufacturing costs and simpleservicing and maintenance operations as compared to a vacuum chamberswhich are open and closed by the provision of doors.

In order that the present invention may be better understood, thefollowing description of preferred embodiments is given by way ofnon-limitative example with reference to the accompanying drawings inwhich:

FIG. 1 is a top plan view of a packaging line including a vacuumpackaging machine which is a first embodiment of the present invention;

FIG. 2 is a schematic sectional side view of a first arrangement for avacuum packaging machine according to the present invention;

FIG. 3 is a schematic sectional side view of a second arrangement for avacuum packaging machine according to the present invention;

FIG. 4 is a schematic sectional side view of a third arrangement for avacuum packaging machine according to the present invention;

FIG. 5 is a schematic sectional side view of a fourth arrangement for avacuum packaging machine according to the present invention;

FIG. 6 is a detailed side view of a vacuum packaging machine accordingto the present invention;

FIG. 7 is a partial enlarged view of the vacuum packaging machine shownin FIG. 6 and showing a vacuum chamber and a drive mechanism for openingand closing a vacuum chamber in an overlapping view;

FIG. 8 is a side view of the drive mechanism of FIG. 7 in isolation in afirst position;

FIG. 9 is a cross-sectional view taken along line IX—IX of the drivemechanism in the first position of FIG. 7;

FIG. 10 is a side view of the drive mechanism in the second position;and

FIG. 11 is a cross-sectional view taken along line XI—XI of the drivemechanism in the second position of FIG. 10.

FIG. 1 is a top plan view of a vacuum packaging machine 1 which is anembodiment of the present invention arranged in a packaging line 13constituted by a series of conveyors. At a bagging section 14, productsare bagged in heat-shrinkable film bags, or alternatively in smallpouches made from thin films, and arranged on line 13 as productpackages 2. A vacuum packaging machine 1 performs a vacuum sealingoperation on the product packages 2 which are then output back onto thepackaging lines 13 which conveys them through a shrink tunnel 15 toperform a heat-shrinking operation. The product packages 2 movecontinuously through the shrink tunnel 15 which is advantageous overheat-shrinking of products in batches where it is difficult to obtainuniform shrinking of the packaging around each product as a result ofcontact or proximity between the various product packages 2.

FIGS. 2 to 5 are sectional side views of various arrangements for thevacuum packaging machine 1. FIGS. 2 to 5 are schematic for ease ofunderstanding of the overall arrangement and operation. Details of thestructure of the vacuum packaging machine are given subsequently.

The vacuum packaging machine 1 has a body 3 supporting a plurality ofvertically stacked vacuum chambers 4. As can be seen in FIG. 1, sincethe vacuum chambers 4 are stacked vertically, they only occupy the samefloor space as a single vacuum chamber. Except as described below, eachvacuum chamber 4 is in itself of conventional construction and performsa vacuum sealing operation in a conventional manner.

Each vacuum chamber 4 has a modular construction allowing vacuumchambers to be added or removed from the vacuum packaging machine 1. Forexample, in the arrangement illustrated in FIG. 2, there are two vacuumchambers 4 a, 4 b. In the arrangements illustrated in FIGS. 3 and 4, anadditional vacuum chamber 4 c has been added so that there are threevacuum chambers 4 a, 4 b, 4 c. In the arrangement illustrated in FIG. 5,there are four vacuum chambers, 4 a, 4 b, 4 c, 4 d.

The vacuum chambers 4 a, 4 b, 4 c, and 4 d each have a respectiveinternal chamber conveyor 5 a, 5 b, 5 c, and 5 d to convey productpackages 2 therethrough, and a respective sealing bar 12 arranged longone side of each chamber extending along the corresponding chamberconveyor 5 a, 5 b, 5 c, and 5 d. Provision of a sealing bar 12 on theside of each chamber conveyor 5 a, 5 b, 5 c, and 5 d facilitatesautomatic feeding and loading is made easier by the bags beingorientated in the same direction.

Each chamber has a respective entrance 6 a, 6 b, 6 c, and 6 d and exit 7a, 7 b, 7 c, and 7 d. Opening and closing of the vacuum chambers isdescribed in more detail subsequently.

At least one in-feed conveyor 8 and at least one out-feed conveyor 9 areprovided on opposite sides of the vacuum chambers 4 facing entrances 6and exits 7. The in-feed and out-feed conveyors 8, 9 are independentlyvertically moveable, for example between a lower-position shown in boldoutline in FIG. 2 for loading and unloading the lower vacuum chamber 4 aand a higher position shown in dotted outline in FIG. 2 for loading andunloading the upper vacuum chamber 4 b.

The in-feed conveyors 8 and the out-feed conveyors 9 have a modularconstruction allowing additional conveyors to be added or removed. Inthe arrangements illustrated in FIGS. 2 and 3 only a single in-feedconveyor 8 and an out-feed conveyor 9 are used. In the arrangementsillustrated in FIGS. 4 and 5, conveyors have been added so that thereare a pair of in-feed conveyors 8 a, 8 b and a pair of out-feedconveyors 9 a, 9 b. Where plural in-feed or out-feed conveyors 8, 9 areprovided, these are arranged in a vertical stack with the in-feedconveyors 8 being moveable together as a unit and the out-feed conveyorsbeing moveable together as a unit.

A fixed input conveyor 10 is provided to receive unsealed productpackages 2 into the machine 1 from station 14 along packaging line 13and supply them to the in-feed conveyor 8. Another fixed output conveyor11 receives sealed packages from the out-feed conveyor 9 and outputsthem along line 13.

In an alternative construction, the at least one in-feed and out-feedconveyors 8, 9 are fixed in the position shown in bold in FIG. 2 and thevacuum chambers 4 are movable together vertically between upperposition, as shown in FIG. 2, for loading and unloading the lower vacuumchamber 4 a and a lower position in which the vacuum chamber 4 b isaligned with in-feed and out-feed conveyors 8, 9 for loading andunloading.

All the conveyors 5, 8, 9, 10, 11 are indexed, that is they are drivento execute an indexing motion.

The vacuum chambers 4 are illustrated as accommodating two productpackages 2, but they may be dimensioned to accommodate any number ofproduct packages 2.

The vacuum packaging machine 1 is operated in a continuous cyclecontrolled by an electronic control unit (not shown), although manualcontrol is an alternative possibility. Loading and unloading of thevacuum chambers 4 is performed in a cyclical sequence and the vacuumchambers are synchronously operated to perform a vacuum sealingoperation on the loaded product packages 2, including vacuumisation andsealing of the product packages 2 using the sealing bar 12. In generalthe provision of plural vacuum chambers 4 allows the vacuum sealingoperation to be performed in one vacuum chamber 4 whilst another vacuumchamber 4 is being loaded and unloaded.

Normally, the at least one in-feed conveyor 8 and out-feed conveyor 9are synchronously moved vertically. An opposed in-feed conveyor 8 andout-feed conveyor 9 adjacent the fixed conveyors 10, 11 are operatedsynchronously to receive product packages 2 from the fixed inputconveyor 10 and to supply sealed product packages to the fixed outputconveyor 11, and are then moved adjacent one of the vacuum chambers 4.Similarly, an opposed in-feed conveyor 8 and out-feed conveyor 9adjacent a given vacuum chamber 4 are operated synchronously to load thegiven vacuum chamber 4 with unsealed product packages 2 andsimultaneously to unload the same vacuum chamber 4 with the sealedproduct packages 2.

The advantage of providing plural in-feed and out-feed conveyors 8, 9(as in the arrangements illustrated in FIGS. 4 and 5) is that a givenvacuum chamber 4 may be loaded and unloaded using a first in-feedconveyor 8 and out-feed conveyor 9 simultaneously with supply to andfrom a second in-feed conveyor 8 and out-feed conveyor 9 from and to thefixed conveyors 10 and 11.

The precise order of operation of the elements of the vacuum packagingmachine 1 in a cycle depends on the number of vacuum chambers 4, in-feedconveyors 8 and out-feed conveyors 9 arranged in the vacuum packagingmachine 1. A possible cycle for the arrangement of the vacuum packagingmachine 1 illustrated in FIG. 2 is as follows and is illustrative of thecycle for other arrangements.

As an arbitrary starting point within the cycle, we can take the pointat which the vacuum sealing operation in the lower vacuum chamber 4 ahas just finished. At this time, the vacuum sealing operation in theupper vacuum chamber 4 b is under-way. The lower vacuum chamber 4 a isopened. Next, the fixed conveyors 10, 11, the in-feed and out-feedconveyors 8, 9 and the lower chamber conveyor 5 a are simultaneouslyoperated (i) to load lower vacuum chamber 4 a with new unsealed productpackages 2 from the in-feed conveyor 8, (ii) to unload sealed productpackages from the lower vacuum chamber 4 a onto the out-feed conveyor 9,and (iii) to supply new unsealed product packages 2 onto the in-feedconveyor 8. Exact synchronization is preferable but some degree ofoverlap is desirable. The lower vacuum chamber 4 a is then closed forcommencement of the vacuum sealing operation, that is vacuumization ofthe chamber 4 a and sealing of the product packages 2 by sealing bar 12.

During the vacuum sealing operation in the lower vacuum chamber 4 a,loading and unloading of the upper vacuum chamber 5 is performed. Theout-feed conveyor 9 is operated briefly to clear sealed products off it.Then the in-feed and out-feed conveyors 8, 9 are raised to the uppervacuum chamber 4 b and when the vacuum sealing operation in the uppervacuum chamber 4 b has finished, the upper vacuum chamber 4 b is opened.Simultaneous operation of the in-feed and out-feed conveyors 8, 9 andthe upper chamber conveyor 5 b loads and unloads the upper vacuumchamber 4 b.

Subsequently, the upper vacuum chamber 4 b is closed and the vacuumsealing operation in the upper vacuum chamber 4 b is commenced. At thesame time, the in-feed and out-feed conveyors 8, 9 are operated to loadand unload the lower vacuum chamber 4 a. That is to say, the in-feed andout-feed conveyors 8, 9 are lowered and then the in-feed conveyor 8 isoperated simultaneously with the fixed conveyor 10 to fill the in-feedconveyor with new product packages 2 from in-feed conveyor 8 while thesealed packages move onto the out-feed conveyor 9.

The cycle then repeats.

Various modifications to the cycle are possible. For example, instead ofsimultaneously loading and unloading a vacuum chamber 4 by operating thein-feed and out-feed conveyor 8, a chamber conveyor 5 and out-feedconveyor 9 together, it is possible to operate in-feed conveyor 8 andout-feed conveyor 9 independently to perform loading and unloadingseparately.

In the second arrangement shown in FIG. 3 employing three verticallystacked vacuum chambers 4 a, 4 b, 4 c, a possible cyclical sequence ofoperation is: to load and unload vacuum chamber 4 a; to commence vacuumsealing operation in the lower vacuum chamber 4 a and simultaneously toload and unload the middle vacuum chamber 4 b; to commence the vacuumsealing operation in the middle vacuum chamber 4 b and simultaneously toload and unload the vacuum chamber 4 c; to commence the vacuum sealingoperation in the upper vacuum chamber 4 c and simultaneously to load andunload the lower vacuum chamber 4 a once its own vacuum sealingoperation has finished.

In the third arrangement shown in FIG. 4, by employing three vacuumchambers 4 a, 4 b, 4 c with a pair of in-feed conveyors 8 a, 8 b and apair of out-feed conveyors 9 a, 9 b it is possible to simultaneously (i)operate one in-feed conveyor and out-feed conveyor (ii) load and unloadproduct packages 2 from one vacuum chamber 4 and (iii) operate the otherin-feed conveyor to fill it with new unsealed product packages 2 and theother out-feed conveyor to empty it of sealed product packages 2. Thissaves time in the operation cycle as compared to arrangements having asingle in-feed conveyor 8 and a single out-feed conveyor 9.

The fourth arrangement illustrated in FIG. 5 has two separated pairs ofvacuum chambers 4 a, 4 b and 4 c, 4 d and a pair of in-feed conveyors 8a, 8 b and a pair of out-feed conveyors 9 a, 9 b having a relativevertical spacing equal to the vertical spacing between the vacuumchambers of each pair 4 a, 4 b and 4 c, 4 d.

In each arrangement, at least some of the vacuum chambers 4 have aregular spacing and the in-feed and out-feed conveyors 8, 9 have arelative spacing equal to the spacing between the vacuum chambers 4,this allowing loading and unloading of respective vacuum chambers 4simultaneously.

Any arrangement of the vacuum packaging machine 1 with a differentnumber of vacuum chambers may be selected to suit the particularpackaging line 13 in which it is employed. Preferably the number ofvacuum chambers is sufficient relative to the length of the vacuumsealing operation to allow the machine to handle the maximum rate ofproduct package through-put on the packaging line. Therefore thepreferred number and configuration of vacuum chambers depends both onthe speed of the line and on the size of the vacuum chambers which isgoverned by the size of the product packaging.

The spacing between the vacuum chambers need not be vertical. They mayinstead be horizontally spaced or in a 2 dimensional array.

FIG. 6 illustrates the detailed structure of the vacuum packagingmachine 1 illustrated schematically in FIGS. 2 to 5, in particular withthe arrangement shown in FIG. 4 of three vacuum chambers 4, two in-feedconveyors 8 and two out-feed conveyors 9.

The in-feed conveyors 8 a, 8 b are mounted on respective supports 16 a,16 b which are together shuttled vertically by linkage to an endlessbelt arrangement 17 driven by a motor 18. Similarly the out-feedconveyors 9 a, 9 b are also mounted on respective supports 51 a, 51 band shuttled vertically together by linkage to an endless beltarrangement 19 driven by a motor 20.

The vacuum chambers 4 a, 4 b, and 4 c each comprise a base 21 a, 21 b,and 21 c respectively, which supports the internal chamber conveyor 5 a,5 b, and 5 c respectively, and a cover 22 a, 22 b, and 22 c respectivelyhaving circumferential hanging walls 23 a, 23 b, and 23 c respectively,which in use form the side walls of the closed vacuum chambers 4 a, 4 b,and 4 c respectively. Various elements (not shown) are attached to thecovers 22 a, 22 b, and 22 c including vacuum pipes, electrical tablesand pneumatic pipes. The covers 22 a, 22 b, and 22 c are fixed to thebody 3, whereas base 21 a, 21 b, and 21 c are arranged to reciprocatevertically to open and close vacuum chambers 4 a, 4 b, and 4 crespectively. This means it is unnecessary to move the elements attachedto covers 22 a, 22 b, and 22 c which enables a simpler design and alsospeeds up opening and closing. When closed, base 21 a, 21 b, and 21 cseals against the hanging walls 23 a, 23 b, and 23 c respectively ofcovers 22 a, 22 b, and 22 c respectively to maintain the vacuum duringvacuumization. Respective pairs of guide frames 52 a, 52 b, and 52 c arefixed to the body 3 to guide the vertical movement of base 21 a, 21 b,and 21 c respectively.

As an alternative, it would be possible to open and close the vacuumchamber 4 by providing doors which may be hinged or which may slideperpendicularly to the movement of the product packages 2, for exampleon opposed trails. However, it is preferable to open and close thevacuum chamber 4 by forming it from at least two parts which arerelatively movable vertically, because this allows a simpler machinedesign, lowers manufacturing costs and simplifies servicing andmaintenance operations. This is particularly the case if one part isfixed, such as the cover 22, to which elements such as the vacuum pipesmay be fixed, so that the movable part, such as the base 21, has onlymechanical elements which are easily moved.

Respective identical drive mechanisms 24 are provided for moving thebase 21 of each vacuum chamber 4 to open and close the vacuum chamber 4.The drive mechanisms 24 are provided on the rear side of the body 3. Thedrive mechanisms 24 for one of the vacuum chambers 4 is illustrated inFIG. 7 in an overlapping view with a vacuum chamber 4 to illustrate thelocation of the drive mechanism 24 and the linkage to the other parts ofthe vacuum packaging machine 1. In FIGS. 8 to 11, a drive mechanism 24is shown in isolation for clarity.

The drive mechanism 24 is driven by a pneumatic cylinder 25 between theposition shown in FIGS. 8 and 9 where the base 21 is lowered and theposition shown in FIGS. 10 and 11 where the base 21 is raised.

The drive mechanism 24 is supported on a first and second mountingblocks 26, 27 fixed to the body 3 of the vacuum packaging machine 1. Thepneumatic cylinder 25 reciprocally drives a rod 28 in and out of thepneumatic cylinder 25. A cap 29 on the end of the rod 28 and the end 30of the pneumatic cylinder 25 opposite to the rod 28 are both pivotallyconnected to respective angular levers 31, 32. The angular levers 31, 32are themselves fixed on an axle 33, 34 rotatably mounted by a bearing toa respective mounting block 26, 27. A respective sector 35, 36 is fixedto each axle 33, 34 so as to rotate with the respective angular lever31, 32. The sectors 35, 36 engage and drive respective cogs 37, 38rotatable mounted on a bearing within the respective mounting blocks 26,27. The cogs 37, 38 are fixed on respective drive axles 39, 40 whichprotrude from the mounting blocks 26, 27 and mount a respective supportlever 41, 42.

Respective tracks 43, 44 are supported by studs 45, 46 fixed by a screwto the end of the respective support levers 41, 42 and positioned toslide along the tracks 43, 44. The tracks 43, 44 are fixed to theunderside of the base 21 of the vacuum chamber 4 and together supportthe base 21.

The operation of the drive mechanism 24 is as follows.

When the base 21 is in its lowered position as illustrated in FIGS. 8and 9, actuation of the pneumatic cylinder 25 causes the pneumaticcylinder 25 and rod 28 to be driven apart. This forces the angularlevers 31, 32 to rotate away from each other, towards the positionillustrated in FIG. 10. This movement of the angular levers 31, 32drives the sectors 35, 36 away from each other which in turns drives thedrive cogs 37, 38 to rotate in opposite directions. Thus the supportlevers 41, 42 connected to the cogs 37, 38 by the support axles 39, 40are rotated in opposite directions towards one another. This causes thestuds 45, 46 to move in an arc towards one another and thereby toreciprocate within the tracks 45, 46 and to raise the tracks 43, 44which raises the base 21 to the position illustrated in FIGS. 10 and 11.

Similarly, actuation of the pneumatic cylinder 25 to retract the rod 28drives motion of the drive mechanism 24 in the opposite direction tolower the base 21.

In addition, the mounting blocks 26, 27 are provided with respectiverotatably mounted arms 48, 49 thereon. The arm 49 of the first mountingblock 26 has a reverse gear 50 which engages the axle 33 of the firstmounting block 26. The arm 48 of the second mounting block 27 is fixedto and rotates with the angular lever 32 supported by the first mountedblock 27. Thus the second arm 49 is rotated in the opposite direction tothe axle 33, that is in the same direction as the first arm 48. The arms48, 49 are linked together by a rod 47 which acts as a linkage tosynchronise rotation of the elements of the drive mechanism 24 mountedto the first and second mounting blocks 26, 27. The rod 47 also providesstructural rigidity between the mounting blocks 25, 26 to avoidmechanical distortion of the guiding frames 52 provided at the sides ofthe vacuum chamber 4.

1. A vacuum packaging machine for performing a vacuum sealing operationon product packages, comprising: a) a permanently vertical stack ofvacuum chambers each arranged to receive at least one unsealed productpackage and operable to perform an independent vacuum sealing operationon the at least one product package, the permanently vertical stack ofvacuum chambers occupying the same size floor space as a single vacuumchamber of said stack; at least one in-feed conveyor operable to load aselected vacuum chamber with the at least one product package, the atleast one in-feed conveyor being vertically movable to select the vacuumchamber to be loaded; and c) at least one out-feed conveyor operable tounload a selected vacuum chamber with the at least one product package,the at least one out-feed conveyor being vertically movable to selectthe vacuum chamber to be unloaded.
 2. The vacuum packaging machine ofclaim 1 comprising a plurality of in-feed conveyors which are verticallymovable together to select the vacuum chamber to be loaded.
 3. Thevacuum packaging machine of claim 2 wherein the permanently verticalstack of vacuum chambers have a regular spacing between the vacuumchambers, and the plurality of in-feed conveyors have a relative spacingequal to the spacing between the vacuum chambers.
 4. The vacuumpackaging machine of claim 1 comprising an internal conveyor in eachvacuum chamber extending from the at least one in-feed conveyor.
 5. Thevacuum packaging machine of claim 1 comprising a plurality of out-feedconveyors which are vertically movable together to select the vacuumchamber to be unloaded.
 6. The vacuum packaging machine of claim 5wherein the permanently vertical stack of vacuum chambers have a regularspacing between the vacuum chambers, and the plurality of out-feedconveyors have a relative spacing equal to the spacing between thevacuum chambers.
 7. The vacuum packaging machine of claim 1 wherein thepermanently vertical stack of vacuum chambers are vertically fixed inposition.
 8. The vacuum packaging machine of claim 1 wherein the atleast one in-feed conveyor and the at least one out-feed conveyor aresynchronously vertically movable.
 9. The vacuum packaging machine ofclaim 1 wherein the at least one in-feed conveyor and the at least oneout-feed conveyor are independently vertically movable.
 10. The vacuumpackaging machine of claim 1 comprising a fixed input conveyor and afixed output conveyor.
 11. A vacuum packaging machine for performing avacuum sealing operation product packages, comprising: a) a permanentlyvertical stack of vacuum chambers each arranged to receive at least oneunsealed product package and operable to perform an independent vacuumsealing operation on the at least one product package, the permanentlyvertical stack of vacuum chambers occupying the same size floor space asa single vacuum chamber of said stack, and the permanently verticalstack of vacuum chambers being movable together vertically between anupper position and a lower position; b) at least one in-feed conveyoroperable to load a selected vacuum chamber with the at least one productpackage; and c) at least one out-feed conveyor operable to unload aselected vacuum chamber with the at least one product package.
 12. Avacuum packaging machine according to claim 11, comprising a pluralityof in-feed conveyors which are operable to load a selected vacuumchamber with the at least one product package.
 13. The vacuum packagingmachine of claim 12 wherein the permanently vertical stack of vacuumchambers have a regular spacing between the vacuum chambers, and theplurality of in-feed conveyors have a relative spacing equal to thespacing between the vacuum chambers.
 14. A vacuum packaging machineaccording to claim 11 comprising an internal conveyor in each vacuumchamber extending from the at leas one in-feed conveyor.
 15. A vacuumpackaging machine according to claim 11, comprising a plurality ofout-feed conveyors which are operable to unload a selected vacuumchamber with the at least one product package.
 16. The vacuum packagingmachine of claim 15 wherein the permanently vertical stack of vacuumchambers have a regular spacing between the vacuum chambers, and theplurality of out-feed conveyors have a relative spacing equal to thespacing between the vacuum chambers.
 17. The vacuum packaging machine ofclaim 11 wherein the at least one in-feed conveyor and the at least oneout-feed conveyor are vertically fixed in position.
 18. The vacuumpackaging machine of claim 11 wherein the permanently vertical stack ofvacuum chambers are vertically movable together relative to the at leastone in-feed conveyor to select the vacuum chamber to be loaded.
 19. Thevacuum packaging machine of claim 11 wherein the permanently verticalstack of vacuum chambers are vertically movable together relative to theat least one out-feed conveyor to select the vacuum chamber to beunloaded.